Interpretive Summary: Broiler carcasses can be contaminated with the human pathogen Campylobacter. The numbers of Campylobacter on broiler carcasses go down due to the scalding step (a hot water dip used to facilitate feather removal). However, the numbers go back up when the carcass passes through automatic feather pickers which operate by beating feathers out of the skin with rubber fingers. This study was undertaken to determine if Campylobacter can be forced out of the vent due to the action of the picker. Campylobacter free carcasses were intra-cloacally inoculated with Campylobacter and passed through an automatic picker. Following defeathering, Campylobacter was detected on the breast skin indicating escape from the cloaca. Another experiment was conducted in which carcasses with naturally contaminated intestinal tracts were treated to a cloacal plug procedure. This plugging, done prior to defeathering, interfered with the occurrence of Campylobacter on the breast skin after defeathering. Breast skin samples from un-plugged carcasses had large numbers of Campylobacter while those from plugged birds had little to no Campylobacter. It appears that a large part of the increase in Campylobacter numbers found on chicken carcasses after defeathering is due to leakage of contaminated feces from the vent.

Technical Abstract:
Live broilers obtained from a commercial processor were transported to a pilot plant and breast skin was sampled by a sponge wipe method before and after defeathering. One of 120 broiler breast skin samples was positive for Campylobacter before defeathering and 95 of 120 were positive after defeathering. In the second set of experiments, Campylobacter-free flocks were identified, subjected to feed withdrawal and transported to the pilot plant. Carcasses were intra-cloacally inoculated with Campylobacter (107 CFU) just prior to entering the scald tank. Breast skin sponge samples were negative for Campylobacter before carcasses entered the picker (0 of 120). After defeathering, 69 of 120 were positive for Campylobacter with an average of log10 2.7 CFU per sample. The third set of experiments was conducted using Campylobacter- positive broilers obtained at a commercial processing plant and transported live to the pilot plant. Just prior to scald, the cloacae were plugged with tampons and sutured shut on half the carcasses. Plugged carcasses were scalded and breast skin samples taken before and after defeathering were compared to those collected from control broilers from the same flock. Prior to defeathering, 1 of 120 and 0 of 120 breast skin sponge samples were positive for the control and plugged carcasses respectively. After passing through the picker, 120 of 120 control carcasses had positive breast skin sponge samples with an average of log10 4.2 CFU per sample. Only 13 of 120 plugged carcasses had detectable numbers of Campylobacter on the breast skin sponge with an average of log10 2.5 CFU per sample.